title: Down-regulation of death-associated protein kinase-2 is required for beta-catenin-induced anoikis resistance of malignant epithelial cells.
abstract: Resistance of solid tumor cells to anoikis, apoptosis induced by cell detachment from the extracellular matrix, is thought to be critical for the ability of these cells to grow anchorage independently within three-dimensional tumor masses and from metastases. Beta-catenin, a major oncoprotein, can inhibit anoikis of cancer cells via unknown mechanisms. In an effort to identify these mechanisms we found that beta-catenin blocks anoikis of malignant kidney and intestinal epithelial cells and promotes their anchorage-independent growth by down-regulating death-associated protein kinase-2 (DAPk-2), a pro-apoptotic protein whose cellular functions have so far remained unexplored. We found that beta-catenin-induced down-regulation of DAPk-2 requires the presence of the transcription factor Tcf-4, a known mediator of beta-catenin signaling. We also observed that DAPk-2 contributes to the execution of anoikis of the non-malignant epithelial cells. Thus, beta-catenin-induced down-regulation of DAPk-2 represents a novel signaling mechanism by which beta-catenin promotes the survival of malignant epithelial cells following their detachment from the ECM and enables these cells to grow in an anchorage-independent manner.
authors.affiliation: Department of Pediatrics, Atlantic Research Centre, Dalhousie University, Halifax, Nova Scotia B3H 4H7, Canada.
authors.forename: Hongbing
authors.initials: H
authors.lastname: Li
authors.forename: Gibanananda
authors.initials: G
authors.lastname: Ray
authors.forename: Byong Hoon
authors.initials: BH
authors.lastname: Yoo
authors.forename: Mete
authors.initials: M
authors.lastname: Erdogan
authors.forename: Kirill V
authors.initials: KV
authors.lastname: Rosen
mesh_terms: D023102:Anoikis; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism*; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D003110:Colonic Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D064550:Death-Associated Protein Kinases; D015536:Down-Regulation; D004847:Epithelial Cells / Q000378:metabolism* / Q000473:pathology; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007680:Kidney Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D009154:Mutation / Q000235:genetics; D011485:Protein Binding; D034741:RNA, Small Interfering / Q000235:genetics; D000073940:Transcription Factor 4; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000235:genetics; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism*
chemical_list: D051017:Apoptosis Regulatory Proteins; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D004268:DNA-Binding Proteins; D034741:RNA, Small Interfering; C532096:TCF4 protein, human; D000073940:Transcription Factor 4; D014157:Transcription Factors; D051176:beta Catenin; C579104:DAPK2 protein, human; D064550:Death-Associated Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases